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Section of a cell wall; hemicellulose in green. Based on the structural difference, like backbone linkages and side groups, as well as other factors, like abundance and distributions in plants, hemicelluloses can be categorized into four groups as following: [4] 1) xylans, 2) mannans; 3) mixed linkage β-glucans; 4) xyloglucans.
Hemiacetals form in the reaction between alcohols and aldehydes or ketones. Using an acid catalyst, the reaction proceeds via nucleophilic attack of the carbonyl group by the alcohol. [4] A subsequent nucleophilic attack of the hemiacetal by the alcohol results in an acetal. [2] Solutions of simple aldehydes in alcohols mainly consist of the ...
Used in a more general sense, the term X,Y-acetal also refers to any functional group that consists of a carbon bearing two heteroatoms X and Y. For example, N,O-acetal refers to compounds of type R 1 R 2 C(OR)(NR' 2) (R,R' ≠ H) also known as a hemiaminal ether or Aminal, a.k.a. aminoacetal.
Structure of a plant cell. Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae.Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or ...
A particular problem is that hemicellulose is covalently linked to lignin, usually through ferulic acid component of the lignin. This makes it difficult to extract the sugars necessary for conversion to biofuels. [11] Next to cellulose hemicellulose is the second most abundant source of carbohydrates in a plant. [12] cellulose is a homopolymer ...
Adenosine, a component of RNA, results from the sugar ribose and adenine via the formation of an N-glycosidic bond (shown as the vertical line between the N and the sugar cycle) Glycosidic bonds of the form discussed above are known as O-glycosidic bonds , in reference to the glycosidic oxygen that links the glycoside to the aglycone or ...
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The glycosidic bond can be formed between any hydroxy group on the component monosaccharide. So, even if both component sugars are the same (e.g., glucose), different bond combinations (regiochemistry) and stereochemistry ( alpha- or beta- ) result in disaccharides that are diastereoisomers with different chemical and physical properties.